JPH01197731A - Transmission type screen - Google Patents

Abstract

PURPOSE:To reduce reflection loss by forming a Fresnel lens on the whole surface of the light outgoing side of a Fresnel screen and on the outer periphery of the light incident side of that, and permitting the outgoing and incoming sides to share the refracting power of the lens only on the outer periphery of the screen. CONSTITUTION:The transmission screen 1 is composed of the double-sided Fresnel screen 1a and a lenticular screen 1b. Out of all the composing screens the screen 1b is positioned on the nearest side to the incoming light source. The screen 1b forms the Fresnel lens on the whole light outgoing plane and on the periphery Y of the light incoming plane; the outgoing and incoming sides are permitted to share the refracting power of the lens only on the outer periphery of the screen. In addition, when the Fresnel lens is shaped in accordance with formulas, the reflection loss of light forming an image is reduced on a lens surface and light loss is also reduced; thereby a satisfactory image is obtained. In formulas, theta2 represents the angle that a light beam comes out to the surface of the Fresnel lens; theta3 represent the angle that it makes incident on that surface; n represents the refraction factor of screen material; (d+d') represents the area ratio of the outgoing plane of a prism to the whole area.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transmissive screen for rear projection television, and more specifically, to a transmissive screen for a rear projection television, and more specifically, a short projection distance lens is provided in front of a television picture tube (CRT). Even if it is used for such a projection television, which is arranged to reduce the overall size of the set, there will be a reflection loss of the magnified image light by the lens on the screen surface, and a loss of reflection at the edge of the Fresnel lens that makes up the screen. The present invention relates to such a transmissive screen that reduces light loss and the like.

[Prior Art] FIG. 6 is an explanatory diagram showing an example of a general rear projection television system.

In the figure, 1 is a transmission type screen, and one side is formed with a Fresnel lens la''.
and a lenticular screen 1b having one side formed of a lenticular lens. 2 is a television picture tube, and 3 is a projection lens.

The image displayed on the picture tube 2 is enlarged by a projection lens 3 and projected onto a screen 1, and transmitted through the screen 1 to the viewing side. The Fresnel screen 1a1 is for converting a ray of light incident from the lens 3 at an angle θ into parallel light and outputting the parallel light. If the light emitted from the Fresnel screen 1a1 remains parallel light, the lenticular screen 1b
If it deviates even slightly from the screen surface of ", the image cannot be seen, so if the parallel light is scattered slightly and the angle is within a certain range with respect to the screen surface of screen 1b,
This is to make the image visible to all viewers.

Now, the present invention relates to the above-mentioned transmission screen, but conventional transmission screens for projection televisions generally take the form of a flat plate mixed with a light diffusing agent, or a Fresnel lens with a Fresnel lens formed on the - side. There are lenticular type screens with a lenticular lens formed on the negative side, lenticular type screens with a lenticular lens formed on the negative side, combinations of the above two types of screens, and screens with a Fresnel lens formed on the negative side and a lenticular lens formed on the other side. However, among these, directivity, brightness 2
Due to superior optical properties such as color unevenness, a combination of a lenticular lens and a Fresnel lens has come to be used.

Furthermore, since it is easy to minimize the moiré pattern caused by the lines of the concentric edges of the Fresnel lens and the joint lines of each lens surface of the lenticular lens, it is possible to Screens with oriented lenses (such as the example shown in Figure 6) are becoming mainstream.

Examples of patent publications that describe these matters in detail include JP-A-57-210332 and JP-A-59-48.
No. 744 can be mentioned.

[Problem to be solved by the invention]

It is thought that projection television sets will become more compact in the future, but in this case, it will be mainstream to use a lens with a short projection distance (hereinafter sometimes referred to as a short projection distance lens) as a projection lens. It will be.

If a short projection distance lens is used under these circumstances, the angle of view will inevitably become larger. For this reason, it becomes necessary that the Fresnel lens, which has the function of converting light that enters with such a large angle of view into parallel light, also has a short focus. As a method to achieve this short focal length, (a) the material of the Fresnel lens has a high refractive index, and (b)
There are two possible methods: reducing the radius of curvature of the lens surface, but since the former is difficult due to various material constraints, it is necessary to achieve this using the latter method.

However, when the radius of curvature of the lens surface is reduced, conventional Fresnel screens have the following problems. That is, (1) the angle of incidence of the magnified image light by the lens on the screen surface increases at the periphery of the screen, and as a result, the loss of I1 of the light due to reflection increases;

■The edge area of the Fresnel lens that makes up the screen increases toward the periphery of the screen, and light loss increases accordingly.

As a means to solve the above problems, the utility model was introduced in 1984-5.
As shown in the third embodiment in Japanese Patent No. 2417, a method of arranging a plurality of Fresnel lenses to shorten the combined focal length can be considered, but the reflection loss of the image light occurring on each lens surface and Considering the occurrence of ghosts caused by reflection and the increase in cost, this is not necessarily a good idea.

The present invention has been made in view of the above-mentioned conventional technical circumstances, and therefore, an object of the present invention is to eliminate the loss of magnified image light due to reflection from the Fresnel screen and the loss of light generated by the edge portion of the Fresnel lens. It is an object of the present invention to provide a transmission type screen including such a Fresnel screen which minimizes the loss of personnel.

[Means to solve the problem]

The purpose of the above is to form a Fresnel lens using the entire viewing side (the side where light comes out) of the Fresnel screen that makes up the transmission screen, and to form a Fresnel lens on the opposite side of this side (the side where light enters). This is achieved by forming a Fresnel lens on the outer periphery of the screen, and sharing the refractive power of the lens between the light output side and the light input side only at the outer periphery of the screen. Reflection loss can be reduced. On the other hand, the light loss at the edge of the screen is zero at the center of the screen and is sufficiently small at the outer periphery of the screen, so that it does not adversely affect the image.

FIG. 1 is an explanatory diagram showing one embodiment of the present invention, and if this diagram is compared with FIG. 6, the means for solving the problem becomes clear. That is, in FIG. 1, the Fresnel screen 1
It can be seen that a Fresnel lens is formed on the outer periphery of the light incident side of a as shown by Y, albeit slightly. This point is where the present invention differs from the prior art, and also represents a means for solving the problem.

[Effect]

Next, we will discuss the cases where a Fresnel lens is formed only on one side of the Fresnel screen, that is, the side where light enters, and the case where a Fresnel lens is formed only on the other side of the Fresnel screen (the side where light exits). Edge loss 2 Radiation loss will be explained, and then the operation of the Fresnel screen according to the present invention will be explained with reference to the drawings.

FIG. 7 shows, when the location of the projection lens is S, its projection distance L1, screen size L2, and incident angle α to the screen periphery, 7 (where i means input, n=1. 2...) is an explanatory diagram showing the relationship between the following.

When the screen size L2 is an effective size of 45 (inches) and the aspect ratio of the screen surface is 3:4, the screen height L3 and the screen width L4 are expressed as follows.

L3 = 45 (inch) x 25.4 (mm/inch) x 3
15', 686 (L, = 45C inch) x 25.4 (mm/inch) x 4
15! #9 1 5 (+mn) Projection magnification is 9~1O
The projection distance Ll of a general projection lens, which is about double that, is currently about 1300 (mm).

From these relationships, the angle between the enlarged projection light from the lens to the center of each side and the diagonal corner of the effective screen and the screen normal is determined as al(=jan-' L3/2 Ll= 14.
8°ζ15°...(1) α, , = tan-' L4/ 2 Ll= 19.
4"i 19°...(2) α,, = jan-' Lz/ 2 L+= 23.
7°', 24'''... (3) However, in the future, projection lenses with short projection distances will become mainstream, and for example, it is possible to realize a projection lens with a projection distance of about 60% of that of tax law lenses. Therefore, this lens has a very large angle of view when the screen size is the same.

This means that the incident angle to the screen periphery is α5.

α, 2. α8. means that it becomes larger. This (1
).

If calculated using formulas (2) and (3), L+'=130
0X0.6"1800 (mm) α1° = jan-
'L3/2 Ll'=23.2 "i23'αrt
' = tan-' L4/2 Ll'=29.8
':30'α, 3° = tan-' Lx/2 L
+'=35.5#36°, and it can be seen that the angle of incidence of the enlarged image light on the outermost portion of the screen is 1.7 times as large.

FIG. 8 is a cross-sectional view of a Fresnel lens that uses the entrance surface Fresnel method.

That is, assuming a Fresnel screen in which one side is formed of a Fresnel lens, and selecting the side where the Fresnel lens is formed as the side on which the enlarged image light is incident, such a method is called an entrance surface Fresnel method.

In the entrance plane Fresnel method, many Fresnel lenses are formed on the side where the image light enters.
FIG. 8 is an enlarged sectional view of one of them. In the figure, β1 is the prism angle, al is the incident ray, and α is the incident angle.

The angle of incidence α of each Fresnel lens differs depending on whether it is located at the center or at the periphery of the Fresnel screen. In order to emit light rays having different incident angles equally as parallel light, it is necessary to change the prism angle θ1 for each Fresnel lens in accordance with the difference in the incident angle α5.

In the incidence plane Fresnel method, when all the light emitted from the Fresnel screen is parallel light, the change in the prism angle θ with the incident angle αil as a parameter is the same (the edge loss of the Fresnel lens with the incident angle α as a parameter) ,
FIG. 9 is a graph showing the relationship between reflection losses.

In FIG. 9, the horizontal axis represents the incident angle αi1, and the vertical axis represents the prism angle θ1. Edge loss 1 reflection loss is taken. The calculation basis for such a graph will be explained below.

In the case of the incidence plane Fresnel method, as shown in FIG. 8, the following equation holds between the incident angle α,1 of the enlarged image light, that is, the incident light ray a1, and the prism angle θ, according to Snell's law.

5in(cr;+101)=n cos(180°-(
β1+β1))...(4) However, n indicates the refractive index, and if the material is acrylic, n''
, 1.5 n cos BI= sin 7 , −
- (5) (4) If β1 is deleted from equation (5), β1 is shown as follows.

(6) In the above equation (6), if we set r+=0 from the condition that the emitted light ray a1° is parallel light, then α. θ can be calculated using l as a parameter.

Next, in the incident surface Fresnel method, the loss at the edge part P:l"Px" of the square lens surface is (d+d
It is indicated by ゛).

This means that the image light C4+'d4 incident from the edge portion P x' P :l'' of each lens surface is refracted by the lens surface, and then
This becomes abnormal light and does not emerge from the section d of the image light exit side, resulting in a loss.

Furthermore, after being refracted by the lens surface, the video signal b4゜c4 that travels between the joint part p,1 of the lens surface and the tip p3'' of the edge similarly becomes abnormal light and is reflected at the inner d゛ of the exit side of the image light. This does not become light emitted from the section, but results in a loss.

The loss at the edge explained above can be calculated by the following equation.

・・・・・・(7) However, n indicates the refractive index, and when the material is acrylic, n L
:, 1.5 In the above equation (7), if we set T, = 0 from the condition that the exiting ray is parallel light, then the incident angle α, , (prism angle θ3)
The edge lft loss (d+d') can be calculated using as a parameter.

Next, let's consider reflection loss.

It is generally known that the reflection intensity with respect to the incident angle of light at a boundary between media having different refractive indexes is expressed by the following equation.

That is, where, nl is the refractive index of the first medium n2 is the refractive index of the second medium 1, is the angle of incidence from the first medium to the second medium 12 is the angle of incidence in the second medium Refraction angle: 9: Reflectance of horizontally polarized waves 3: Reflectance of vertically polarized waves Further, the energy of this reflected wave (reflected light) is given by the following equation.

E (energy of reflected light) = r, "+r,"...
(10) From the above equation (lO), the reflection loss can be calculated using the incident angle as a parameter under the condition that the emitted light beam is parallel light.

FIG. 9 shows the relationship between the various losses and prism angle θ in the entrance plane Fresnel method, which were determined as described above. From the figure, at the screen diagonal where the incident angle is 36° (see α13 in Figure 7), the reflection loss is 32%, the edge lfl loss is 61%, and the prism angle θ1 is 40''.
It can be seen that the loss is very large.

FIG. 11 is a sectional view of a Fresnel lens that uses the exit surface Fresnel method.

In other words, assuming a Fresnel screen with one side formed of a Fresnel lens, and selecting the side where the Fresnel lens is formed as the image light exit side, that is, the viewing side, this method can be used as the exit surface Fresnel screen. (Incidentally, the Fresnel screen la shown in FIG. 6 uses this exit surface Fresnel method).

In the exit surface Fresnel method, a large number of Fresnel lenses are formed on the side from which the image light exits.
FIG. 11 is an enlarged sectional view of one of them.

In Fig. 11, as in the case of the incidence plane Fresnel method,
According to Snell's law, the prism angle θ2 is sin ff1z
”” 71 CoSβ, ・−・−・(
11) However, if n is the refractive index of acrylic, then n 嬌1.5n cos(180°-θ, -β,)=s, 1n
(It's 100) (12) If β2 is eliminated from the above equations (11) and (12) and θ2 is found, the following equation is obtained.

(13) Next, loss due to edges does not exist in principle in the case of the exit surface Fresnel method, but in reality, as is clear from Fig. 11, loss due to edges incident light a
z'' is not refracted in a predetermined manner and a non-emission area e occurs, which causes deterioration in image quality such as moiré.

Here, the following formula is applied to find the non-emission area.

Mlcos　θz/sin　θz=1 However, Ml is the length of the edge portion.

M 1 / tan θz=1 Ml-tan θ2 where Mlsin αit”e therefore e = tan θ2 SIn 1lriz
...'' (14) Also, the reflection loss can be determined in the same manner as in the case of the input plane flat channel method using the above-mentioned equations (8), (9), and (10).

FIG. 12 shows the incident angle α in the exit surface Fresnel method.
12 as a parameter, and the relationship between prism angle θ21 reflection loss and non-emission area when the light emitted from the Fresnel screen becomes parallel light.At the screen diagonal where the incident angle to the Fresnel lens is 366, , the prism angle θ2 is 58°2 reflection (zero loss is 11%, non-emission area ratio (in Fig. 11, the ratio of non-emission area e when the vertical dimension of the Fresnel lens is 1) is 40%, and reflection Although the loss of one member is relatively small, the non-emission area ratio is 40%, resulting in moiré and deterioration of image quality.

As mentioned above, in a projection television set using a short projection distance lens, in order to make the light emitted from the Fresnel screen parallel light, in the entrance surface Fresnel method, edge 1N loss 2 reflection loss increases, It has been found that in the exit surface Fresnel method, although the loss of image light is reduced, the non-emission area increases, causing a factor of image quality deterioration such as moiré.

Therefore, in the present invention, by manufacturing a Fresnel screen in which both sides are formed of Fresnel lenses, that is, a double-sided Fresnel screen, and optimizing the shape of the Fresnel lens, the edge loss of image light is reduced by 1. It is intended to have low radiation loss and to minimize non-reflective areas that cause moiré.

Referring again to FIG. In the figure, l is a transmission type screen, which is composed of a double-sided Fresnel screen 1a and a lenticular screen lb. la is a double-sided Fresnel screen, but the viewing side (light output side) is entirely covered with Fresnel lenses, while the other projection lens 3 side (light input side) is formed with a Fresnel lens. As shown by Y, there is a Fresnel lens b only on the outer periphery.
<It is formed. In other words, although 1a is a double-sided Fresnel screen, it is basically based on the exit surface Fresnel system in which a Fresnel lens is formed entirely on the light exit side.

There are two reasons for this: ■ There is no edge loss, and ■ Reflection loss is lower than that of the incident surface Fresnel method. This is because it can be reduced by increasing the amount of the agent. We investigated the reflectance change of the exit surface Fresnel method in more detail.

In Fig. 13, the prism 1 of the Fresnel lens is shown at each image height (normalized and displayed by the outermost length of the screen) when the projection distance N (hereinafter abbreviated as OBD) of the projection lens is changed.
It shows the change in one angle θ2, and it can be seen that it is greatly affected by the change in OBD.

FIG. 14 similarly shows the change in reflection loss (%). It can be seen that this is greatly influenced by changes in OBD.

0BD800au by material with refractive index n # 1.5
When we prototyped a Fresnel screen using the Fresnel type entrance surface for the projection lens marked *, and visually evaluated the deterioration of image quality due to edge loss, it was almost impossible to judge if the loss was less than 20%.

Here, the Fresnel lens (Y of la in FIG. 1) provided on the incident surface is connected to the Fresnel screen 1 as shown in FIG. 1A.
Assuming that the diagonal dimension of a is 100, it is desirable to form it in the remaining outer 20% of the area excluding 80% of the center (80% or more of the diagonal). The reason for this is: (1) If this were not the case, the reflectance would increase significantly at the Fresnel lens interface on the exit surface of the screen, as shown in FIG. ■The maximum horizontal dimension of the screen is diagonal 8
0% (however, the aspect ratio is 3:4), and if the area is larger than this, only the four corners of the screen will have Fresnel lens shapes on both the entrance and exit surfaces. Therefore, moiré caused by misalignment of the center of the Fresnel lens on the two surfaces, the light entrance surface and the light exit surface, is not noticeable.

In this case, when a Fresnel lens is provided over 80% or more of the diagonal of the incident surface, the loss at the edge is as described in (7) above.
It is obtained by transforming the formula.

On the other hand, regarding reflection loss, see (8) and (9) above.
, can be obtained using equation (10).

(Example〕 The present invention will now be described in detail with reference to the drawings.

It has already been mentioned that FIG. 1 is an explanatory diagram showing one embodiment of the present invention. In Fig. 1, the differences from the conventional technology are as follows.
It was also mentioned earlier that the outer peripheral portion of the Fresnel screen la is formed as a double-sided Fresnel lens (a point where a Fresnel lens is newly formed in the Y portion).

FIG. 2 is a sectional view of the double-sided Fresnel lens portion (including the Y portion) on the outer periphery of the Fresnel screen 1a in FIG.

In the figure, it can be seen that a Fresnel lens with a prism angle of θ4 is formed on the incident side of the image light a, and a Fresnel lens with a prism angle of θ4° is formed on the exit side of the image light a. .

Now, in Figure 2, on the plane of incidence, according to Snell's law, sin (α14+θ<)−n sin (θ4+α4
) Therefore, similarly at the exit surface, n5in(θ4°-α4)-sinθ4”...
...(16) If we rearrange this, we can obtain the incident angle αi4 by both equations (15) and (17) above.
It is possible to find the change in the prism angle θl of the exit surface Fresnel lens with respect to the output surface Fresnel lens.

In FIG. 2, the screen thickness 2I has a sufficiently small effect on the lens effect and can be ignored.

Next, in the Fresnel screen 1a as a main part of an embodiment of the present invention, the light emitted from the Fresnel screen is parallel light and the prism angle of the Fresnel lens on the entrance surface is such that the edge loss at the outermost portion of the screen is 20% or less. θ4 and the prism angle θ4 of the exit surface Fresnel lens are determined for each image height (relative image height 1.0 is 4572 inches in this example) using the projection pressure i%il (OBD) of the projection lens 3 as a variable. Shown in Figure 3.

In Figure 3, when the relative image height is 80% or more, the refractive power of the Fresnel lens is not only borne by the Fresnel lens on the exit surface, but also shared by the Fresnel lens on the entrance surface. It can be seen that the prism angle of 04° is decreasing. Furthermore, it can be seen that the shorter the projection distance (OBD) of the projection lens, the larger the prism angle θ4° of the exit surface Fresnel lens. On the other hand, under conditions where the edge loss is set to 20% or less, on the other hand, the prism angle θ4 of the incident surface becomes small.

FIG. 4 shows the reflection loss in the Fresnel lens on the incident surface and the exit surface described above.

As is clear from FIG. 4, compared to the conventional Fresnel screen in which a Fresnel lens is provided only on the exit surface, the Fresnel screen according to the present invention, in which Fresnel lenses are provided on both the exit surface and the entrance surface, has a reflection loss of 10%. It can be seen that the reduction can be achieved by more than %.

In Figure 5, the refractive index of the screen material is 1.5, the projection distance of the projection lens is 800 mm, and the screen size is 4.
FIG. 3 is a characteristic diagram showing the optical performance of the Fresnel screen according to the present invention when the diameter is 5 inches.

Comparing this with the optical performance of the entrance surface Fresnel method shown in FIG. 9 and the optical performance of the exit surface Fresnel method shown in FIG. 12, it can be seen that the following effects are achieved at the outermost periphery of the screen.

■Reflection loss is 9.3%, which is 1 for the exit surface Fresnel method.
This is a 7% reduction compared to 0%. Also, it is less than 1/3 compared to 35% of the incidence plane Fresnel method.

■The non-emission area is 40% of the output surface Fresnel method is 298
8%, a decrease of 26%.

(2) The edge loss is less than 20%, which is less than 1/3 of the 61% of the incidence plane Fresnel method, so there is no problem in practical use.

As described above, in the present invention, not only the entire surface of the exit surface (viewing side) is formed with a Fresnel lens, but also a Fresnel lens is formed on the outer periphery of the entrance surface (here, the picture tube side that is the image projection tube). By providing two sides of the conventional single-sided Fresnel
It is possible to create a screen with brighter surroundings and less moiré interference than the two methods (incident surface Fresnel method and exit surface Fresnel method).

As an embodiment of the present invention, FIG. 1 shows a combination of a double-sided Fresnel screen la and a lenticular screen lb. It goes without saying that the present invention can be realized even if the screens are combined or even if the Fresnel lens shape on the projection lens 3 side is a linear Fresnel shape as shown in FIG. 1B.

The above embodiments have been explained only in the case where a Fresnel lens is provided at the periphery of the entrance surface and the entire surface of the exit surface, but even when a Fresnel lens is provided at the periphery of the exit surface and the entire surface of the entrance surface. It goes without saying that this method has similar effects and is included within the technical scope of the present invention.

〔Effect of the invention〕

According to the present invention, a Fresnel lens is formed on the outer periphery of the picture tube side surface of the Fresnel screen, which is one of the screens constituting the transmission screen, and on the entire viewing side surface, and the shape of each lens is adjusted. By optimally designing
Even when applied to a projection television using a short projection distance lens with a large angle of incidence on the screen, reflection loss,
It is possible to realize a transmissive screen with less reflection at the screen edges (and a reduced non-emission area), which minimizes disturbances such as moiré on the screen.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention, FIGS. 1A and 1B are front views of specific examples of the Fresnel screen shown in FIG. 1, respectively, viewed from the light incident side, and FIG. 3 is a sectional view of the outer peripheral part of the Fresnel screen in an embodiment of the present invention, and FIG. 3 is a characteristic diagram showing the relationship between the prism angle and relative image height in the Fresnel screen as the main part in an embodiment of the present invention in comparison with that in the prior art. FIG. 4 is a characteristic diagram that similarly shows the relationship between reflection loss and relative image height of such a Fresnel screen in comparison with that of the prior art, and FIG. 5 is a characteristic diagram that shows a specific example of the optical performance of such a Fresnel screen. Figure 6 is an explanatory diagram showing a general rear type projection television system, Figure 7 is an explanatory diagram showing the angle of incidence on the screen, Figure 8 is a cross-sectional view of a Fresnel screen that uses the incident plane Larenel type, and Figure 9 is an explanatory diagram showing the angle of incidence on the screen. A characteristic diagram showing a specific example of the optical performance of a Fresnel screen that uses the entrance surface Fresnel method. Figure 10 is a cross-sectional view that is a redrawn version of FIG. 8 for convenience of explanation. Figure 11 uses the exit surface Fresnel method. A cross-sectional view of a Fresnel screen, Fig. 12 is a characteristic diagram showing a specific example of the optical performance of a Fresnel screen that uses the exit surface Fresnel method, and Fig. 13 shows the relationship between the prism angle and relative image height of the Fresnel screen that uses the exit surface Fresnel method. FIG. 14 is a characteristic diagram showing the relationship between reflection loss and relative image height of a Fresnel screen employing the exit surface Fresnel method. Explanation of symbols 1... Transmissive screen, 1a... Double-sided Fresnel screen, tb... Lenticular screen, 2...
...Picture tube, 3...Projection lens agent Patent attorney Akio Namiki III Figure @ 2 Figure 1J! 1 prisoner ilB Fig. 13 Fig. @ 5 Person shooting angle (CX = 4) 嶌6 ■ 117 Fig. IIK8 Fig. 110 Fig. 0 Fig. 111 Fig. 1112 Fig. 1f];

Claims (1)

[Claims] 1. In a transmission screen composed of a plurality of screens, at least one of the plurality of screens has a Fresnel lens on both its light entrance surface and light exit surface. What is claimed is: 1. A transparent screen characterized by being a screen formed by 2. In the transmission screen according to claim 1, in the one screen, a Fresnel lens is formed only on the outer periphery of the light entrance surface of the screen, and a Fresnel lens is formed only on the outer periphery of the light entrance surface, and a Fresnel lens is formed on the light exit surface of the screen. A transmission type screen characterized by a Fresnel lens formed over the entire surface. 3. The transmissive screen according to claim 2, wherein the one screen is located closest to the light source of the incident light among the plurality of screens constituting the transmissive screen. Transparent screen. 4. In a transmissive screen composed of a plurality of screens, on the light incident side screen surface of at least one screen among the plurality of screens, more than 80% of the center on a diagonal line passing through the center position thereof. A Fresnel lens with a prism angle θ_3 is formed in the outer region, and
When a Fresnel lens with a prism angle θ_2 is formed on the entire surface of the screen surface on the light exit side of a sheet of screen, the prism exit surface is A transmission screen characterized in that a loss area (d+d') satisfies the following condition when the entire area of the prism exit surface is 1. d+d'≦0.2 d+d'=tanθ_3(tanα_i_3(tanγ
_3/n)) However, α_i_3=θ−θ_3, γ_3=
θ'-θ_2θ: Incident angle of the light ray on the Fresnel lens surface θ': Outgoing angle of the light ray from the Fresnel lens surface n: Refractive index of the screen material 5. In the transmission screen according to claim 4, the outer region A transmission screen characterized in that a Fresnel lens formed at a prism angle θ_3 is a linear Fresnel lens.